The long-term goal of the proposed research is to describe neuronal mechanisms involved in the initiation and visual guidance of eye movements and in the selective fixation of targets. The ultimate objective is to understand the neural basis of these normal physiological processes, the disruption of which can cause severe impairments: from abnormal eye movements (dysmetria) to so-called visual neglect. Microelectrode recordings will be made from single neurons of monkeys performing various oculomotor tasks such as foveation, fixation, tracking and anticipation of stationary and moving targets. The first brain structures that will be explored are the thalamus (region of the internal medullary lamina) and the cerebellum (vermis and flocculus). For each nerve cell, visual and/or eye movement properties will be first investigated independently, then they will be studied in relation to each other (in cells exhibiting both). Thus, neuronal mechanisms subserving visuo-oculomotor integration will be sought by analyzing: (1) the visual properties of the neurons, with reference to those stimulus parameters which are determinants of movements (e.g., spatial characteristics of responses), (2) in the same or neighboring neurons, the pattern of firing accompanying eye movements of different natures, (3) the relations between visual and eye movement properties.